In a process for manufacturing an electronic product such as a Large Scale Integration (LSI), a process of forming a thin film is performed. As a method of forming the thin film, a film forming method based on a dry (gas phase) processing is widely used. Such a dry processing includes supplying a raw material gas used to form a thin film into a processing chamber of a substrate processing system, and forming the thin film on a substrate to be processed (e.g., silicon wafer) loaded into the processing chamber.
A raw material of the thin film is classified into two types: one is in a gaseous state in room temperature, and the other is in a liquid or solid state in room temperature. The gas raw material in the gaseous state may be directly supplied into the processing chamber as a raw material gas. However, the liquid or solid raw material should be vaporized before being supplied into the processing chamber. In this case, a gas supply apparatus is required to include an additional vaporizer which vaporizes the liquid or solid raw material into the raw material gas.
In such gas supply apparatus, a liquid or solid raw material is received and vaporized in a raw material container. The raw material container functions as the vaporizer. The raw material vaporized inside the raw material container, which is hereinafter referred to as the “raw material gas,” is provided to a gas supply line together with a carrier gas supplied into the raw material container. The raw material gas and the carrier gas are transferred through the gas supply line to be supplied to the processing chamber.
Thereafter, a film forming processing is performed inside the processing chamber. In this case, a supply amount of the raw material gas supplied into the processing chamber is controlled based on the amount of the raw material gas per unit time vaporized inside the raw material container and a flow rate of the carrier gas supplied into the raw material container. Controlling the supply amount of the raw material gas is one of important factors for optimizing, e.g., for forming the thin film to have a uniform thickness, a film forming rate of the thin film or the like, for each process.
The amount of the raw material gas per unit time is mainly controlled by increasing or decreasing a heating temperature of the raw material container (temperature control). The flow rate of the carrier gas is controlled using a mass flow controller (flow rate control).
However, when optimizing the supply amount of the raw material gas for each process, if the flow rate of the carrier gas is increased, it has been confirmed that the particles generated inside the processing chamber tend to increase in the film forming process, for example. This may cause the particles to be attached to the formed thin film or be introduced in the formed thin film, which results in deterioration in quality of the formed thin film.